By running NIS, the system administrator can distribute administrative databases, called maps, among
a variety of servers (master and slaves). The administrator can update those databases
from a centralized location in an automatic and reliable fashion to ensure that
all clients share the same naming service information in a consistent manner throughout
NIS was developed independently of DNS and has a slightly different focus. Whereas
DNS focuses on making communication simpler by using machine names instead of numerical
IP addresses, NIS focuses on making network administration more manageable by providing centralized
control over a variety of network information. NIS stores information not only about
machine names and addresses, but also about users, the network itself, and network
services. This collection of network information is referred to as the NIS namespace.
Note - In some contexts machine names are referred to has host names or machine
names. This discussion uses machine, but some screen messages or NIS map names might
use host or machine.
NIS uses a client-server arrangement. NIS servers provide services to NIS clients. The
principal servers are called master servers, and for reliability, they have backup, or
slave servers. Both master and slave servers use the NIS information retrieval software
and both store NIS maps.
NIS uses domains to arrange the machines, users, and networks in its namespace.
However, it does not use a domain hierarchy; an NIS namespace is flat.
Thus, this physical network would be arranged into one NIS domain.
An NIS domain cannot be connected directly to the Internet using just NIS.
However, organizations that want to use NIS and also be connected to the
Internet can combine NIS with DNS. You can use NIS to manage all
local information and use DNS for Internet host lookup. NIS provides a forwarding
service that forwards host lookups to DNS if the information cannot be found
in an NIS map. The Solaris system also allows you to set up
the nsswitch.conf file so that hosts lookup requests go only to DNS, or
to DNS and then NIS if not found by DNS, or to NIS
and then DNS if not found by NIS. See Chapter 2, The Name Service Switch (Overview) for details.